Italian prosecutors say Swiss authorities have seized about $6 trillion of fake U.S. Treasury bonds in Switzerland as part of a joint Italian-Swiss operation.
Authorities said they have arrested eight people accused of cross-border fraud and other financial crimes.
The operation was carried out by Italian and Swiss authorities after a year-long investigation.
The fake securities, which amount to more than one-third of U.S. national debt, were seized in January from a Swiss trust company.
The U.S. Embassy in Rome has congratulated Italy on the success of the operation, saying in a statement that the bonds were "apparently part of a plan to defraud some Swiss banks."
In September 2009, Italian police seized $116 billion in falsified bonds and arrested two Filipino nationals carrying them at Milan's airport.
Compiled from agency reports